Counting circuits



Jan. 9, 1962 J, CULUS, JR 3,016,473

COUNTING CIRCUITS Filed May 29, 1959 INPUT dl INVENTOR.

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United States Patent O 3,016,473 COUNTING CIRCUITS .lohn Cullis, Jr.,PlainiieldN.J., assigner to Burroughs Corporation, Detroit, Mich., acorporation of Michigan Filed May 29, 1959, Ser. No. 816,815 Claims..(Cl. S15-8.5)

This invention relates to counting circuits and particularly to countingcircuits employing multi-position counting tubes.

One type of multi-position counting tube is known as a magnetron beamswitching tube and includes a plurality of groups of electrodes, at eachof which an electron beam may be formed and from each of which an outputsignal may be obtained. Generally, in using such a tube in a countingcircuit, after a predetermined counting operation has been performed,the electron beam is cleared from the group of electrodes to which it isflowing and the beam is reset at a predetermined zero position, whichrepresents the starting point for the next counting cycle. Many circuitsare known for clearing and resetting lan electron beam in a beamswitching tube, and, while these circuits are generally satisfactory,each has a specific utility and kmay not be universally applicable. Thepresent invention is particularly concerned with zero-setting anelectron beam where simplicity and economy are desirable and high speedof operation is not a primary requirement.

In addition, a problem arises in multiple stage counters using amagnetron beam switching tube for each stage. Genreally, the O or restposition of each tube is also the position from which a carry pulse istransmitted from one tube to the next tube in the count-ing chain. Thus,when a tube is reset and the beam forms in the zero position, the usualoutput carry pulse also appears. However, he generation of this carrypulse is an undesirable Aadjunct to the reset operation, and its effectmust be counteracted in some manner.

Accordingly, the purposes and objects of the invention are concernedwith the provision of a novel beam clearing and zero-setting circuit foruse with a multiple output electron beam switching tube, the circuitbeing characterized by its comparative simplicity and eiliciencycombined with a satisfactory speed of operation.

The objects of the invention are also concerned with the provision of animprovedY counting circuit using magnetron beam switching tubes andhavingrimproved means for clearing and resetting an electron beam andfor counteracting the eiect of a carry pulse generated during theresetting operation. t

In brief, the circuit of the invention employed with a magnetron beamswitching tube, for example a Type 6700 tube, includes means forarbitrarily selecting one t of the tube positions or groups ofelectrodes as the zero position which represents the starting positionin a counting cycle. Resetting circuit means are provided coupled to thetube position which is adjacent to, and lagging, the zero position forfor-ming a-beam at said lagging position. Means are also providedcoupled to the switching elec- ICC FIG. 2 is a schematic representationof the tube 'of FIG. 1 and a circuit embodying the invention; and

FIG. 3 is a schematic representation of a multiple stage counterembodying the invention.

The circuits described below are particularly suitable for use with amulti-position .electron beam tube such' as the Type 6700 magnetron beam:switching tube.` This type of tube is shown in FIG; 1 as'tube `10` vandincludes, brielly, an envelope 12 which contains a centrallongitudinallyelongated cathode 14 and ten groups'of'electrodes spaced radiallyequidistantlyfrorn the cathode'iand surrounding the cathode. Each groupof electrodes includes a generally U-shaped elongated spade electrode 16and a generally L-shaped target electrode 18 positioned so that eachtarget occupies the space between adjacent spade electrodes. Each spadeelectrode serves to form and hold an electro-n beam on its correspondingtarget electrode. A generally rod-like switching electrode 20 is alsoincluded in each group of electrodes and'is positioned between one edgeof each target electrode and the adjacent spade electrode. The switchingelectrodes are known as switching grids. An open-ended cylindricalpermanent magnet 22 is provided Surrounding the tube envelope landcoaxial therewith. The magnet' provides an axial lmagnetic field whichis utilized in conjunction with electric -iields Within the tube to formand switch an electron beam from the cathode to each of the groups ofelectrodes. The direction in which the beam switches, that is clockwiseor counterclockwise, is always the same and is determined by theorientation of the electric and magnetic fields.

Briefly, in operation of tube 10, electrons emitted by the cathode areretained at the catohde if each of 4the spades, targets and switchinggrids carries its normal operating electrical potential. When a spade orswitching grid experiences `a suitable lowering of its potential, anelectron beam is formed and directed to the corresponding targetelectrode. The electron beam may be switched from one target electrodeto the next by thus suitably altering the electrical potentials of aspade or switching grid. Under normal operating conditions, wheneverelectrode voltages are such that a beam might be supported at sever-a1positions, the beam will switch to the most leading position and lock inat this position.

In the circuit of FIG. 2, the tube 10 is -shown in schematic, linearform with only tive positions or groups of electrodes shown and numbered0, 1, 2-. 8, 9, with the 0 group representi-ng the first position in acounting cycle and group 9 representing the last position. In thecircuit, the cathode 14 is connected through a suitable resistor 24 toground. The cathode is'also coupled through a capacitor 26 to a source28 of positive pulses 30 which are used to clear an electron beam fromany position in the tube. Each of the spade electrodes 16is coupledthrough a spade load resistor 32 to a spade buss 34, which is coupledthrough a common trode at the lagging position for simultaneouslycausing van electron beam to switch to the predetermined zero positionas soon as it begins to form at the lagging position. When the beamswitches to and sets at the zero position, a'carry pulse is generated,the effect o-f which is counteracted by the overwhelming inuence oftheresetting means. f

The invention is described in greater detail by reference to the drawingwherein: A

FIG. l is a perspective view, partly in section, of an electron tubeused in practicing the invention;

spade resistor 36 to a buss 38 which is connected to Aa suitable`positive D.C. power supply Vp of ,about 300 volts. According to theinvention, a source 40 of negative zero-set pulses 42 is coupled througha capacitor 44 to the 9 spade, that is, the spade electrode at the 9position. The 9 position is the position adjacent to and lagging the 0position, which is the first-position in the counting cycle of the tube.The 0 position is the one at which it is desired to reset the electronbeam.

The target electrodes 18 are connected' through suitable pairs of loadresistors S0 and 52 to the buss 38 which is `coupled to the positiveD.C. power supply Vp. In

addition, an auxiliary output tap 56 is provided at each target betweenthe resistors of the pairs for connection to a utilization device orcircuit, if desired. Thus, the

target electrodes may be connected, for example to the cathodes of acathode glow indicator tube, or to ya printing mechanism or the like.

The switching grid electrodes 20 are connected in pairs, with the gridsat the even-numbered positions being connected together in one set andthe grids at the odd-numbered positions being connected together inanother set. Each set of grids is then connected to a driver circuit tobe described below so that first one and then the other set of grids isenergized and, thus, the beam is caused to move from position toposition in the tube.

The driver for the beam switching tube includes a bistable multivibrator60 which is coupled to two cathode follower amplifiers at 62, one ofwhich controls the operation of the even-numbered switching grids andthe other of which controls the operation of the odd-number v switchinggrids. The multivibrator may be of any wellknown form and may include,for example, a iirst triode 66 including cathode 68, control grid 70,and anode 72, and a second triode 74 including a cathode 76, a controlgrid 7S, and an anode 80. The cathodes 68 and '76 are coupled togetherthrough a resistor 82 to ground. A capacitor 84 is provided across theresistor 82. The control grid 70 of the first triode 66 is coupledthrough suitable resistors 86 and 8S to ground, and the control grid 78of the second triode 74 is connected through a resistor 90 to ground.The control grid 7) of the rst triode is connected through a parallelcombination of resistor 92 and capacitor 94 to the anode 3G of thesecond triode. The control grid 78 of the second triode is similarlyconnected through a parallel combination of resistor 96 and capacitor 98to the anode of the iirst triode. The anodes 72 and 80 of the triodesare connected through suitable load resistors 100 and 102 to a commoncoupling capacitor 104 and then to a source 166 of negative input pulses108. The anodes are also connected through a common resistor 110 to asuitable power source. The source 40 of negative reset pulses is coupledthrough a suitable capacitor 112 to the control grid of the iirsttriode. 'Ihis connection may be made specifically to a point between thetwo resistors v86 and 88.

The cathode followers at 62 include a first triode 114 having a cathode116, control grid 118, and an anode 120, and a second triode 122 havinga cathode 124, control grid 126, and anode 128. The two anodes 120 and128 are connected together to a power source not illustrated. The twocontrol grids 118 and 126 are connected through suitable resistors 130and 132, respectively, to ground, `and the control grid of the rsttriode is coupled through a coupling capacitor 134 having a neon voltageregulator tube 136 in parallel with it to the anode of the second triode74 of the multivibrator. The control grid 126 of the second cathodefollower triode is similarly coupled through a parallel combination ofcoupling capacitor 138 and a neon voltage regulator tube 140 to theanode of the rst flip-flop triode 66. The cathode 116 of the firstcathode follower triode is coupled through a parallel combination ofresistor 142 and capacitor 144 to ground, and it is also coupled to theset of odd-numbered switching grids of the tube 10. The cathode of thesecond cathode follower triode is coupled through a parallel combinationof resistor 146 and capacitor 148 to ground and to the set ofeven-numbered switching grids of the tube 10.

In operation of the cricuit of FIG. 2, let it be assumed that the tubeis counting in normal fashion and that an electron beam is beingswitched from position to position under the inuence of switching pulseswhich areapplied rst to one set of switching grids and then to the other.set of switching grids. During the switching operation, themultivibrator circuit operates in conventional fashon with lfirst onetriode conducting and then the other conducting, with the first triode66 controlling the operation of cathode follower 64 to provideswitchingpulses for the set of even-numbered switching grid electrodes,and the second triode 74 controlling the operation of cathode follower62 to provide switching pulsesfor' the set of odd-numbered switchinggrids.

When it is desired to clear the electron beam and reset it at the zeroposition, a positive pulse 30 is applied to the cathode 14 from thesource 28. This pulse has an amplitude of about 250 volts and raises thepotential of the cathode to such a level that a beam cannot be sustainedin the tube, and it is cleared from the position at which it is formed.After the beam lhas been cleared, a negative reset pulse 42 from thesource 40 is applied both to the 9 spade and to the con-trol grid 70 ofthe triode 66 of thelmultivibrator. This pulse 42 has an amplitude ofabout 250 volts and lowers the potential of the 9 spade suiiiciently sothat an electron beam forms and ows to the 9 position. At the same time,the multovibrator is set so that the triode 74 is in the conductivestate. When the triode 74 becames conductive, its anode Si) is reducedin potential and the control grid 118 of the cathode follower tube 114,similarly, is reduced in potential. At the same time, the cathode of thetube 114 becomes more negative, and this negative potential is appliedt-o the odd-numbered gn'd electrodes, including the 9 grid. T heapplication of this negative potential to the 9 grid causes the electronbeam which is present at the 9 position to switch immediately to thezero position and the desired reset operation is accomplished.

A multiple stage counter using the principles of the invention is shownin Iblock diagram in FIG. 3. ln the circuit, two or more beam switchingtubes 15d and 152, of the type shown in FIG. l, are connected in series,with each tube being provided with essentially the same circuit elementsas shown in FIG. 2. A iirst bistable multivibrator driver 154 isprovided for tube 150 and has two output lines, one line 156 connectedto the even-numbered switching electrodes of tube and the other line 158connected to the `odd-numbered switching electrodes of tube 154i. Themultivibrator circuit 154 is provided with an input terminal 160 bymeans of which input counting pulses are applied, and it is alsoprovided with a reset terminal 162 connected as in FIG. 2.

The second beam switching tube 152, similarly, is provided with abistable multivibrator driver 164 having two output lines166 and 168connected to the evennumbered grids and to the odd-numbered gridsthereof, respectively. The input lead 170 to the multivibrator 164 iscoupled to the 0 target of the tube 150 which provides carry pulseswhich `act as input driving pulses therefor. The second multivibrator164 is also provided with a reset terminal y172. The 9 spades of bothtubes 150 and 152 are `also provided with reset termin-als 174 and 176,respectively, connected as in FIG. 2. Tube 152 is also provided with anoutput or carry terminal 177 for transmitting carry pulses to the nextstage of the counter if one is provided.

In the circuit of FIG. 3, input pulses applied to terminal 160 of themultivibrator 154 are negative pulses of about 55'volts. Reset pulsesapplied to .terminal'162 of multivibrator 154, terminal 172 of themultivibrator 164, and terminals 174 and 176 of the tubes 150 and 152are negative pulses of about 250 volts. The carry pulses from the tubes150 and 152 are negative pulses of about 150 volts. p

In operation of the counter circuit of FIG. 3, each input pulse to themultivibrator 154 provides an output pulse on one or the other of theoutput lines l.156er 15S and these output pulses applied to theswitching electrodes of tube 156 cause an electron beam to switch fromposition to position inthe tube. When the beam in the tube 150 reachesthe end of its counting cycle and passes from the 9 position to the Oposition, a carry pulse from the 0 vtarget is applied to the input ofthe second multivibrator 146 and provides anV output signal therefromwhich causes an electron beam in the second beam switching tube 152 toswitch by one position` AtA some time in the counting cycle when it isdesired to reset one or both tubes 150 and 152, a reset pulse is appliedto both multivibrators y154 and 164 and to both 9 spade electrodes oftubes 150 and 152. The application of the reset pulse to the 9 spadeelectrodes causes an electron beam to form in the positions `asdescribed above. The formation of an electron beam in the 0 position oftube 150 provides a carry pulse which might ordinarily operate themultivibrator `164 to cause the beam in the second tube 15-2 to switch.However, the reset pulse which is applied simultaneously to themultivibrator circuits is of such magnitude, about 250 volts, that itoverwhelms the pulse from the 0 target, about l() volts, which thus hasno effect on the second multivibrator 164. The reset pulse is ofsuciently long time duration that its effect on the multivibratorexceeds that of the carry pulse. Thus, the reset operation is achievedwithout adverse effects from a carry pulse generated at the same time.

What is claimed is:

1. A counter circuit including a magnetron beam switching tube having acathode and a plurality of groups of electrodes each comprising acounting position; each group of electrodes including a target electrodewhich receives an electron beam and produces an output signal therefrom,a spade electrode which holds an electron beam on its associated targetelectrode, and a switching electrode which serves to switch an electronbeam from one group of electrodes to the next; circuit means coupled tosaid switching electrodes for applying pulses thereto and causing anelectron beam to switch from position to position; beam resetting meanscoupled to one of said positions to form lan electron beam thereat, saidresetting means also being coupled to said circuit means to energize thesame and apply a pulse to the switching electrode at said one positionto cause the electron beam to switch to the next position atsubstantially the same time that it begins to form at said one position.

2. A counter circuit including a magnetron beam switching tube having acathode and a plurality of groups of electrodes each comprising -acounting position; each group of electrodes including a target electrodewhich receives Ian electron beam and produces an output signaltherefrom, la spade electrode which holds an electron beam on itsassociated target electrode, and 'a switching electrode which serves toswitch an electron beam from one group of electrodes to the next; saidswitching electrodes being connected in two sets, one set including theodd-numbered switching electrodes and one set including theeven-numbered switching electrodes; a bistable multivibrator having twooutput lines, one output line being connected to one set of switchingelectrodes and the other output line being connected to the other set ofswitching electrodes; beam resetting means coupled Ito one of saidpositions to form an electron beam thereat, said resetting means alsobeing coupled through said multivibrator to act on the switchingelectrode at said one position to cause the beam to switch to the nextposition.

3. A counter circuit including a magnetron beam switching tube having acathode and a plurality of groups of electrodes each comprising acounting position; each group of electrodes including a target electrodewhich receives an electron beam and produces an output signal therefrom,a spade electrode which holds an electron beam on its associated targetelectrode, and a switching electrode which serves to switch an electronbeam from one group of electrodes to the next; said switching electrodesbeing connected in two sets, one set including the odd-numberedswitching electrodes and one set including the even-numbered switchingelectrodes; a bistable multivibrator having .two output 1ines,'oneoutput line being connected to one set of switching electrodes and theother output line being connected to the other set of switchingelectrodes; beam resetting means `coupled to one of said positions toform an electron ybeam thereat, said resetting means also being coupledto said multivibrator to cause said multivibrator to apply a switchingpulse to the switching electrode at said one position to cause the beamto switch to the next position.

4. A counter circuit including a magnetron beam switching tube havinga-cathode and a plurality of groups ofV electrodes each comprising acounting position; each group of electrodes including a ytargetelectrode-which receives an electron beam and produces an output signaltherefrom, a spade electrode which holds an electron beam on itsassociated target electrode, and a switching electrode which serves toswitch an electron beam from one group of electrodes to the next; saidswitching electrodes being connected in two sets, one set including theoddnumbered switching electrodes and one set including the even-numberedswitching electrodes, a bistable multivibrator having two output lines,one output line being connected through a rst cathode follower amplierto one set of switching electrodes and the other output line beingconnected through a second cathode follower amplifier to the other setof switching electrodes; beam resetting means coupled to one of saidpositions to form an electron beam thereat, said resetting means alsobeing coupled through -said multivibrator and itscathode follower to acton the switching electrode at said one position to cause the beam toswitch to the next position.

5. A counter circuit including a magnetron beam switching tube having acathode and a plurality of groups of electrodes; each group ofelectrodes including a target elect-rode which receivesV an electronbeam and produces an output signal therefrom, a spade electrode whichholds an electron beam on its associated target electrode, and aswitching electrode which serves to switch an electron beam from onegroup of electrodes to the next; one position in said -tube selected tobe the zero position at which an electron beam is to be formed; beamresetting means coupled to the spade electrode at the adjacent laggingposition for initiating the formation of an elect-ron beam at thelagging position, -said resetting means also being coupled to theswitching electrode at said lagging position so that when said resettingmeans is operated to form a beam at said lagging position the electronbeam immediately switches from said lagging position to the selectedzero position.

6. A counter circuit including a magnetron beam switching tube having -acathode and a plurality of groups of electrodes; each group ofelectrodes including a target electrode which receives an electron beamand produces an output signal therefrom, `a spade electrode which holdsan electron beam on its associated target electrode, and a switchingelectrode which serves to switch an electron beam from one group ofelectrodes to the next; switching means coupled to said switchingelectrodes for causing an electron beam to switch from position .toposition; one position in saidtube being selected to be the zeroposition at which an electron beam is to be formed; beam resetting meanscoupled to the spade electrode at the adjacent lagging position forlowering the spade potentiall thereat and thereby forming an electronbeam at the lagging position; said resetting means also being coupled tosaid switching means for energizing the switching electrode at saidlagging position so that an electron beam immediately switchesfrom saidlagging position to the selected zero position.

7. A multiple stage counter including a plurality of magnetron beamswitching tubes each having a cathode anda plurality of lgroups ofelectrodes; each group of electrodes including a target electrode whichreceives an electron beam and produces an output signal therefrom, aspade electrode which holds an electron beam on its associated targetelectrode, and a switching electrode which serves to switch an electronbeam from one group vof electrodes to the next; a bistable multivibratorcoupled to the input-of each tube; signal carry means coupling oneposition of one tube to the multivibrator associated with the nextytube; beam resetting means coupled to each tube and to eachmultivibrator; the effect of said beam resetting -means on saidmultivibrators being adapted to exceed the effect of said signal carrymeans thereon. f

8. A multiple stage counter including a plurality of magnetron beamswitching tubes each having a cathode and a plurality of groups ofelectrodes; each group of electrodes including a target electrode whichreceives an electron beam and produces an output signal therefrom, aspade electrode which holds an electron beam on its associated targetelectrode, and a switching electrode which serves to switch an electronbeam from one group of electrodes to the next; a bistable multivibratorcoupled to the input of each beam switching tube; signal carry meanscoupled between one position of one tube and the input of themultivibrator associated With the next tube and adapted to transmit acarry pulse thereto; beam resetting means coupled to each tube and toeach multivibrator and adapted to apply reset pulses thereto; said resetpulses being of greater amplitude and longer time duration than saidcarry pulses so that said reset pulses serve to set said multivibratorin a preferred operating condition in spite of the presence of a carrypulse at the multivibrator.

9,. A counter circuit including a magnetron beam switching tube having acathode and a plurality of groups of electrodes each comprising acounting position; each group of electrodes including a target electrodewhich receives an electron beam and produces an output signal therefrom,a spade electrode which holds an electron beam on its associated targetelectrode, and a switching electrode which serves to switch an electronbeam from one group of electrodes to the next; means coupled to one ofsaid positions to form an electron beam thereat; and beam-switchingmeans. coupled to all of said switching electrodes; said beam-settinglmeans being coupled to and adapted to energize said beam-switching meansat substantially the same time that it acts to set a beam at said oneposition whereby an electron beam is se at said one position andswitched from said one position at substantially the same time.

10. A counter circuit including a magnetron beam switching tube having acathode and a plurality of groups of electrodes each comprising acounting position; each group of electrodes including a target electrodewhich receives an electron beam and produces an output signal therefrom,a spade electrode which holds an electron beam on its associated targetelectrode, and a switching electrode which serves to switch an electronbeam from one group of electrodes to the next; beam-switching meanscoupled to said switching electrodes and adapted to cause an electronbeam to switch from position to position; and beam-setting means,coupled to one of the electrodes in one of said groups of electrodesadjacent to the position at which it is desired to set an electron beam;said beam setting means also being coupled to said beam switching meansfor causing it to perform its function on the switching electrode atsaid one position at substantialiy the same time as said beam settingmeans performs its function whereby a beam which tends to form at saidone position is immediately switched to the next desired position.

References Cited in the le of this patent UNITED STATES PATENTS2,807,748 Lee Sept. 24, 1957 2,839,702 Fan et al June 17, 1958 2,856,558Cola Oct. 14, 1958 2,871,399 Scuitto Jan. 27, 1959

